Screenshot/MSNBC Bernie Sanders had difficulty explaining his biggest campaign platform this week in a Daily News interview, and Hillary Clinton seized her chance to strike.

In a Wednesday appearance on MSNBC's "Morning Joe," the Democratic frontrunner attacked Sanders for being unprepared to defend in detail his break-up-the-banks agenda.

Clinton accused Sanders of not doing "his homework" and questioned whether he would be able to deliver on his campaign promises after he seemed uncertain of how he'd actually accomplish his goals.

"I think he hadn't done his homework and he'd been talking for more than a year about doing things that he obviously hadn't really studied or understood," Clinton said, "and that does raise a lot of questions."

She continued: "Really what it goes to is for voters to ask themselves: Can he deliver what he is talking about? Can he really help people? Can he help our economy? Can he keep our country strong?"

Sanders, who has been battling Clinton for the Democratic presidential nomination, told the New York Daily News that he didn't know whether the Federal Reserve had the authority to break up the big Wall Street banks he decries on the campaign trail.

He also said he hadn't studied the legal implications of doing so, and he couldn't explain how he would have gone about prosecuting major Wall Street executives after the 2008 financial crisis.

"I look at it this way: The core of his campaign has been 'break up the banks,' and it didn't seem in reading his answers that he understood exactly how that would work under Dodd-Frank, exactly who would be responsible, what the criteria were," Clinton said Wednesday.

"And that means you can't really help people if you don't know how to do what you are campaigning on what you say you want to do."